R Kotz

University of Vienna, Wien, Vienna, Austria

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Publications (203)362.3 Total impact

  • R Kotz
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    ABSTRACT: The first trend-setting development of megaprostheses was initiated by Martin Salzer who introduced a ceramic prosthesis system in Vienna in 1972 for proximal humeral resection in patients with sarcoma and Ewing's sarcoma. Up until 1982, custom-made prostheses for the distal but also for the proximal femur were used for cementless implants with stem and side plates with screws. The Howmedica Modular Resection System (HMRS) exists since 1988. At the same time as the HMRS system was developed for the lower extremity, a system was also devised for the upper extremity, the Howmedica Humerus Modular Resection System, and the Global Modular Replacement System (GMRS) has been available since 2002.
    Der Orthopäde 10/2010; 39(10):922-30. DOI:10.1007/s00132-009-1567-7 · 0.67 Impact Factor
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    ABSTRACT: Local recurrence (LR) in osteosarcoma is associated with very poor prognosis. We sought to evaluate which factors correlate with LR in patients who achieved complete surgical remission with adequate margins. We analyzed 1355 patients with previously untreated high-grade central osteosarcoma of the extremities, the shoulder and the pelvis registered in neoadjuvant Cooperative Osteosarcoma Study Group trials between 1986 and 2005. Seventy-six patients developed LR. Median follow-up was 5.56 years. No participation in a study, pelvic tumor site, limb-sparing surgery, soft tissue infiltration beyond the periosteum, poor response to neoadjuvant chemotherapy, failure to complete the planned chemotherapy protocol and biopsy at a center other than the one performing the tumor resection were significantly associated with a higher LR rate. No differences were found for varying surgical margin widths. Surgical treatment at centers with small patient volume and additional surgery in the primary tumor area, other than biopsy and tumor resection, were significantly associated with a higher rate of ablative surgery. Patient enrollment in clinical trials and performing the biopsy at experienced institutions capable of undertaking the tumor resection without compromising the oncological and functional outcome should be pursued in the future.
    Annals of Oncology 10/2010; 22(5):1228-35. DOI:10.1093/annonc/mdq589 · 6.58 Impact Factor
  • Physikalische Medizin Rehabilitationsmedizin Kurortmedizin 04/2008; 18(2):83-86. DOI:10.1055/s-2007-991133 · 0.45 Impact Factor
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    ABSTRACT: The evaluation of prognosis in patients with osteosarcoma is limited to clinical parameters. Although numerous molecular markers have been studied, none are currently in routine clinical use. The aim of this study was to determine if Livin and Bcl-2, acting as antiapoptotic proteins through different mechanisms, are expressed in osteosarcoma, and whether they can be used as prognostic markers in human osteosarcoma. Tumor specimens of 29 patients with high-grade central osteosarcoma, with complete clinical follow-up for a minimum of 5 years, were studied. The localization and distribution of Livin and Bcl-2 were investigated using immunohistochemistry. Results were correlated with the histological response to chemotherapy, 5-year disease-free and 5-year overall survival. Bcl-2 was expressed only in the cytoplasm of 16/29 cases and there was no statistically significant correlation between expression and any of the studied parameters. Livin was detected in 17/29 cases, in the cytoplasm of all 17 and in the nucleus of only 3 cases. Nuclear expression was significantly correlated with a decreased overall survival (P < 0.0002) compared with those patients without nuclear expression. The results of this study indicate that Bc1-2 and Livin are highly expressed in osteosarcoma cells and that possibly, the evaluation of nuclear Livin expression might be a useful prognostic marker in osteosarcoma.
    Journal of Cancer Research and Clinical Oncology 03/2008; 134(2):237-44. DOI:10.1007/s00432-007-0276-z · 3.01 Impact Factor
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    ABSTRACT: Malignant lesions of the bones and soft tissues require radical or wide resection to achieve adequate therapy. Due to the many developments in terms of adjuvant modalities, diagnostics and surgical expertise today there are several modes of therapy as alternatives to amputation in the treatment of malignant tumours of the shoulder and upper arm. After resection of smaller tumours excellent functional results can be obtained by the use of modular endoprostheses, whereas large neoplasms adjacent to the neurovascular bundle require resection-replantation to allow salvage of the hand. Within the Vienna Bone Tumour Registry, 100 patients out of a total of more than 6500 have been treated for such lesions: 62 received an endoprostheses, 18 resection-replantation and 20 amputation. In cases of primary malignant tumours the incidence of lung metastases was higher in the resection-replantation group (50 %) and amputation group (42 %) than in the prostheses group (11 %), which has been linked to larger tumour size in the former two groups. Radical or wide resections were obtained in 95 % of the prostheses group, as compared to 75 % and 78 % in the amputation group and the resection-replantation group, respectively, due to invasion into the neurovascular bundle. Over time the number of amputations decreased simultaneously with the increase of endoprostheses whereas the number of resection-replantations remained equal at our institution. Amputation today still plays a crucial role in the treatment of intralesionally resected tumours, as surgical contamination can make limb salvage impossible. Therefore, the importance of biopsy in the therapeutical algorithm of bone and soft tissue tumours has to be emphasised again.
    Handchirurgie · Mikrochirurgie · Plastische Chirurgie 03/2008; 40(1):13-8. · 0.54 Impact Factor
  • Handchirurgie · Mikrochirurgie · Plastische Chirurgie 02/2008; 40(1):13-18. DOI:10.1055/s-2007-989418 · 0.54 Impact Factor
  • Osteoarthritis and Cartilage 12/2007; 15. DOI:10.1016/S1063-4584(07)61372-7 · 4.66 Impact Factor
  • Osteoarthritis and Cartilage 12/2007; 15. DOI:10.1016/S1063-4584(07)61870-6 · 4.66 Impact Factor
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    ABSTRACT: Background and Objectives The treatment and outcome of primary malignant bone tumours has changed with the advances in diagnostic and treatment modalities. A trend-analysis on a large cohort of patients with metastatic bone disease was performed.MethodsA retrospective chart review of all cases with metastatic bone disease admitted to a single tertiary orthopaedic referral centre, registered with the Vienna Bone and Soft Tissue Tumour Registry between 1968 and 2003 was conducted. For trend-analysis of frequency, survival, primary site, treatment methods, and others, the 36-year study duration was divided into four periods.ResultsThe study identified 601 females and 580 males (mean: 60 years) with metastatic bone disease. The most common metastases were secondary to breast cancer (n = 275; 23%) and renal cell carcinoma (n = 242; 21%) and the majority were located in the femur (n = 332; 28%) and spine (n = 348; 29%). Overall, the proportion of patients who underwent surgery decreased. At follow-up, 887 (75%) patients were verified to have died of their disease.Conclusions Over the 36-year period, the frequency of bone metastases has increased at our centre. Although survival increased over time, the difference was not significant; this was most likely attributable to the seriousness of cases referred to our tertiary care centre. J. Surg. Oncol. 2007;96:404–410. © 2007 Wiley-Liss, Inc.
    Journal of Surgical Oncology 10/2007; 96(5):404 - 410. DOI:10.1002/jso.20787 · 2.84 Impact Factor
  • P. Vavken, R. Kotz, R. Dorotka
    Zeitschrift für Orthopädie 03/2007; 145(2):152-156. DOI:10.1055/s-2007-965170 · 0.86 Impact Factor
  • P Vavken, R Kotz, R Dorotka
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    ABSTRACT: A systematic review of randomized controlled trials reporting on the comparison of minimally invasive THA and standard incision technique. An online search in Medline, CINAHL,EMBASE, and the Cochrane Controlled Trials Register was performed. Data concerning the endpoints duration of procedure, blood loss,complications, and Harris Hip Score (HHS) were extracted and pooled using a random effects model. 8 Studies observing a total of 917 patients(481 MIS, 436 Std.) were included. The weighted mean difference in duration of the procedures was 4 min, which is not significant(p = 0.21). There was significantly less blood loss in the mini group (p < 0.001). The difference in increases in HHS of averagely 4.14 pts. was only borderline significant (p = 0.06). The complication odds ratio showed no significance (p = 0.71). There is only a marginal difference between these techniques. The minimally invasive total hip replacement is a variance of the standard procedure with better cosmesis. Differences in postoperative rehabilitation, however,are not within the scope of this study.
    Zeitschrift fur Orthopadie und Unfallchirurgie 01/2007; 145(2):152-6. · 0.62 Impact Factor
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    ABSTRACT: To investigate the presence of mesenchymal precursor cells (MPCs) in synovial surface projections of patients with osteoarthritis (OA), to characterize their phenotype and to show their localization. Progenitor cells in synovial surface projections were identified by immunohistochemistry, morphometric analysis and confocal laser scanning microscopy using the following phenotypic markers: STRO-1, CD34, and alpha smooth muscle actin (alpha-SMA). In the synovial tissue of all 21 patients with OA MPCs were detected. Immunohistochemistry and subsequent morphometric analysis showed that approximately twice as many STRO-1+ cells/mm2 were observed in synovial tissue of patients with OA as compared to healthy organ donors and that number of STRO-1+ cells/mm2 correlated with total cell number/mm2. Interestingly, in the synovial tissue of patients with OA, twice as many STRO-1+ cells/mm2 were found in synovial surface projections as compared to the sublining area without villi. Using confocal laser scanning microscopy two populations of STRO-1+ MPCs could be detected in synovial surface projections. Single STRO-1+ cells that co-expressed alpha-SMA resemble a population of pericyte precursors required to stabilize the immature vasculature. The second STRO-1+ cell population that was found lacked alpha-SMA but co-expressed CD34 on their surface with low intensity. Here we can show that in the synovial tissue of patients with OA twice as many STRO-1+ MPCs can be found in synovial surface projections as compared to the sublining area. These cells are preferentially located at the basis and in the protruding end of the synovial surface projection.
    Osteoarthritis and Cartilage 10/2006; 14(9):938-43. DOI:10.1016/j.joca.2006.02.014 · 4.66 Impact Factor
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    ABSTRACT: In a randomised study, 28 patients with a mean age of 62.2 years (32 to 81) with osteoarthritis or avascular necrosis of the hip received either a ceramic-on-ceramic or a metal-on-metal total hip replacement. Apart from the liners the acetabular and femoral components were made of Ti-Al-Nb alloy. The serum aluminium and cobalt levels were measured before, and at one year after surgery. The 15 patients in the ceramic-on-ceramic group had a median pre-operative aluminium level of 1.3 microg/l (0.25 to 8.4) and a cobalt level below the detection limit. At one year the aluminium level was 1.1 microg/l (0.25 to 2.3) and the cobalt level was 0.4 microg/l (0.15 to 0.7). The 13 patients in the metal-on-metal group had a median pre-operative aluminium level of 1.9 microg/l (0.25 to 4.4) and a cobalt level below the detection limit. At one year the median aluminium level was 0.9 microg/l (0.25 to 3.9) whereas the cobalt level was 1.4 microg/l (0.5 to 10.5). This increase in the cobalt level at one year was significant (p < 0.001). Our findings indicate that ceramic-on-ceramic bearings do not cause elevated levels of serum aluminium in the first post-operative year.
    The Bone & Joint Journal 08/2006; 88(8):1003-5. DOI:10.1302/0301-620X.88B8.17870 · 2.80 Impact Factor
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    ABSTRACT: Based on neoadjuvant chemotherapy, the prognosis of osteosarcoma patients has improved dramatically. However, due to therapy resistance in patient subgroups, the development of new treatment strategies is still of utmost importance. The aim of our study was to test the effects of the nitrogen-containing bisphosphonate zoledronic acid (ZOL) on osteosarcoma cell lines (N = 9). Exposure to ZOL at low micromolar concentrations induced a dose- and time-dependent block of DNA synthesis and cell cycle progression followed by microfilament breakdown and apoptosis induction. The ZOL-induced cell cycle accumulation in S phase was accompanied by significant changes in the expression of cyclins and cyclin-dependent kinase inhibitors with a prominent loss of cyclin E and D1. ZOL not only inhibited growth but also migration of osteosarcoma cells. The mevalonate pathway intermediary geranyl-geraniol (GGOH) but not farnesol (FOH) significantly inhibited the anticancer effects of ZOL against osteosarcoma cells. Correspondingly, ZOL sensitivity correlated with the blockade of protein geranylgeranylation indicated by unprenylated Rap1. Overexpression of even high levels of P-glycoprotein, as frequently present in therapy-resistant osteosarcomas, did not impair the anticancer activity of ZOL. Summarizing, our data suggest that ZOL, which selectively accumulates in the bone, represents a promising agent to improve osteosarcoma therapy.
    Journal of Orthopaedic Research 06/2006; 24(6):1145-52. DOI:10.1002/jor.20129 · 2.97 Impact Factor
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    ABSTRACT: Repair of articular cartilage represents a significant clinical problem and although various new techniques - including the use of autologous chondrocytes - have been developed within the last century the clinical efficacy of these procedures is still discussed controversially. Although autologous chondrocyte transplantation (ACT) has been widely used with success, it has several inherent limitations, including its invasive nature and problems related to the use of the periosteal flap. To overcome these problems autologous chondrocytes transplantation combined with the use of biodegradable scaffolds has received wide attention. Among these, a hyaluronan-based scaffold has been found useful for inducing hyaline cartilage regeneration. In the present study, we have investigated the mid-term efficacy and safety of Hyalograft C grafts in a group of 36 patients undergoing surgery for chronic cartilage lesions of the knee. Clinical Outcome was assessed prospectively before and at 12, 24, and 36 months after surgery. No major adverse events have been reported during the 3-year follow-up. Significant improvements of the evaluated scores were observed (P < 0.02) at 1 year and a continued increase of clinical performance was evident at 2 and 3 years follow-up. Patients under 30 years of age with single lesions showed statistically significant improvements at all follow-up visits compared to those over 30 with multiple defects (P < 0.01). Hyalograft C compares favorably with classic ACT and is particularly indicated in younger patients with single lesions. The graft can be implanted through a miniarthrotomy and needs no additional fixation with sutures except optional fibrin gluing at the defect borders. These results suggest that Hyalograft C is a valid alternative to ACT.
    European Journal of Radiology 01/2006; 57(1):3-8. DOI:10.1016/j.ejrad.2005.08.005 · 2.16 Impact Factor
  • Chapter: Osteosarkom
    S. Bielack, A. Zoubek, R. Kotz
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    ABSTRACT: Häufigkeit: In den deutschsprachigen Ländern ist mit etwa 200–300 Neuerkrankungen pro Jahr zu rechnen, d.h., nur etwa 0,1% aller Krebserkrankungen sind Osteosarkome. Bei Kindern unter 15 Jahren liegt dieser Anteil jedoch bei knapp 3%, im Alter von 15 bis 19 Jahren bei über 5%.
    12/2005: pages 5157-5191;
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    ABSTRACT: Zusammenfassung Die autologe Chondrozytentransplantation hat die Behandlung von Knorpeldefekten revolutioniert. In der ursprünglichen Operationstechnik wird der debredierte Defekt mit einem Periostlappen verschlossen, und Chondrozyten in Suspension werden injiziert. Diese Technik hat jedoch einige Nachteile wie Probleme bei der Gewinnung und Befestigung des Periostlappens und Tendenzen zu Hypertrophie und Delamination des Lappens. Mit der Entwicklung von Biomaterialien wurde es möglich, ein sicheres und verlässliches Zelltransportsystem zuschaffen, das darüber hinaus auch die Neubildung von Gewebe begünstigt. Biomaterialien werden intensiv beforscht und sind bereits vielfach in klinischer Anwendung. Die vielversprechenden Ergebnisse dieser neuen Techniken erweitern die Indikationen der zellbasierten Knorpeltherapie und deuten neue Wege für regenerative Knorpelbehandlung an.
    Arthroskopie 08/2005; 18(3):203-208. DOI:10.1007/s00142-005-0325-z
  • M Dominkus, M Sabeti, R Kotz
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    ABSTRACT: Large defects of functional soft tissue structures, e.g., extensor mechanism, ligaments, muscles, and joint capsule, may occur in tumor surgery or revision surgery following conventional joint replacement. Reconstruction can be performed using biological grafts such as free or pedicled tendon-muscle flaps, allografts, or synthetic material. Prerequisites for synthetic material are good biologic tolerance with fibroblastic ingrowth, mechanical resistance to fatigue, and a maximum of tension force with a minimum of elongation. In this study we used a nonresorbable band of longitudinal polyester fibers with a minimal rupture level of 4000 N and an elongation rate less than 7% of its original length. The shape of the band was designed for universal use with 40 cm length and 6 cm width. Its primary indication was augmentation or complete reconstruction of the extensor mechanism of the knee joint after large extra-articular tumor resections in primary bone tumors. Furthermore, its use for hip joint capsule reconstruction in luxation, coverage of megaprostheses of the humerus, and augmentation after biological reconstruction of tendons achieved excellent results.
    Der Orthopäde 07/2005; 34(6):556-9. · 0.67 Impact Factor
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    ABSTRACT: Zusammenfassung Große Defekte funktioneller Weichteilstrukturen wie Streckapparat, Sehnen, Muskel, Gelenkkapsel stellen ein rekonstruktives Problem in der Tumororthopädie, aber auch in der Revisionschirurgie dar. Übliche Rekonstruktionen beinhalten freie oder gestielte Muskellappentransplantationen, Allografts oder synthetisches Material.
    Der Orthopäde 06/2005; 34(6):556-559. DOI:10.1007/s00132-005-0802-0 · 0.67 Impact Factor
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    ABSTRACT: This study was initiated to test the hypothesis that soluble p185(HER-2) could be of value as a diagnostic or predictive marker for patients with malignant bone tumours. Sera of 35 patients with high-grade malignant osteosarcoma (n = 27) and Ewing Sarcoma (n = 8) were tested at the time of diagnosis by ELISA and compared with sera of controls (n = 38) and clinical data. In patients with osteosarcoma and Ewing Sarcoma, levels of sp185(HER-2) did not differ significantly from levels in controls. These results were irrespective of the type of tumour, survival chemotherapy or other clinical variables. p185(HER-2) serum levels do not appear to be of diagnostic or predictive value for differentiation of high-grade osteosarcoma and Ewing Sarcoma.
    Pediatric Blood & Cancer 02/2005; 44(2):163-6. DOI:10.1002/pbc.20217 · 2.56 Impact Factor

Publication Stats

3k Citations
362.30 Total Impact Points


  • 1983–2010
    • University of Vienna
      • Institute of Molecular Pathology
      Wien, Vienna, Austria
  • 1999–2008
    • Medical University of Vienna
      • Department of Orthopaedics
      Wien, Vienna, Austria
  • 1998–2008
    • Vienna General Hospital
      Wien, Vienna, Austria
    • Gesellschaft für Pädiatrische Onkologie und Hämatologie
      Hamburg, Hamburg, Germany
  • 2007
    • Prince Court Medical Centre
      Kuala Lumpor, Kuala Lumpur, Malaysia
  • 2003
    • University of Toronto
      Toronto, Ontario, Canada
  • 1996
    • University of Hamburg
      • Department of Paediatric Haematology and Oncology
      Hamburg, Hamburg, Germany
  • 1994
    • Kyoto University
      • Department of Orthopaedic Surgery
      Kyoto, Kyoto-fu, Japan
  • 1989
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany